Lost wax casting is how most typical
commercial jewelry is created (most wedding rings are made this way!).
The piece starts as a carved wax model. This is finished, smoothed and sized to perfection. An example of some of my wedding bands can
be seen being prepped here.

The waxes are then setup on a stick of wax called a sprue. The sprue holds the ring in place and when the molten metal is poured, creates a
pathway for it to flow into the design. Many wax pieces can be cast at
once.

After the wax pieces are all mounted on a special rubber base, a steel jar
is fitted over the setup. The top of it is open and a
special plaster mix called investment is poured in. That it is left to dry
out for a few hours. The rubber base is then pulled off,
revealing a formed pour spout leading to the waxes, which are now locked
in place in the investment.

The flask is put inside a kiln and heated up over a matter
of several hours. This burns out the wax, revealing a hole in the
desired shape.

The metal of choice (bronze, silver, gold,
etc) is heated till it's molten. At that point, the mold flask is
pulled from the hot kiln, put on a vacuum table, and the molten metal is
poured into the spout. After a few seconds of vacuuming, the flask is
pulled off, dunked in water and the metal piece is revealed. The cast
rings can be seen here. LOTS of cleanup must occur after that.

Because of casting safety issues (we are dealing with molten
metal and burning wax!), I do all my casting at the Lawrence Arts
Center in their well outfitted jewelry classroom. I teach jewelry
classes there and am happy to share the process!